Restore eng/Version.Details.xml and eng/Versions.props to main values

Previous rebase inadvertently reverted FSharpPreReleaseIteration from 4 to 3
and changed the VMR Source SHA to an older value.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: T-Gro

eng/Version.Details.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Dependencies>
-  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="542fea6988c173c64859bab06c9d2d100034843c" BarId="305563" />
+  <Source Uri="https://github.com/dotnet/dotnet" Mapping="fsharp" Sha="1a405c76db678301b6f6f5b22d2a63a152c26b97" BarId="309188" />
   <ProductDependencies>
     <Dependency Name="Microsoft.Build" Version="18.6.0-preview-26180-08">
       <Uri>https://github.com/dotnet/msbuild</Uri>

eng/Versions.props

@@ -14,7 +14,7 @@
   <PropertyGroup>
     <!-- Don't use the built in support for pre-release iteration. The nuget repack task doesn't support
          the iteration format at the moment. https://github.com/dotnet/arcade/issues/15919 -->
-    <FSharpPreReleaseIteration>3</FSharpPreReleaseIteration>
+    <FSharpPreReleaseIteration>4</FSharpPreReleaseIteration>
     <PreReleaseVersionLabel>preview$(FSharpPreReleaseIteration)</PreReleaseVersionLabel>
     <!-- F# Version components -->
     <FSMajorVersion>11</FSMajorVersion>